Load detecting seat

ABSTRACT

A load detecting seat comprises a pair of supporting members provided at the right and left sides of a seating surface of a seat cushion of the load detecting seat for supporting the seat cushion on a floor, a seat frame serving as a skeletal structure of the load detecting seat, a load detecting means provided between one supporting member and the seat frame for detecting a load applied to the seating surface of the seat cushion of the load detecting seat, a rod bridging the one supporting member and the other supporting member and securely fixed to be unrotatably relative to the one supporting member at a fixing portion of the rod, a connecting member fixed to the rod and rotatably supported by the seat frame for applying a torsion force to the rod due to the load applied to the seat frame, and the load detecting means is provided at a portion of the rod.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 U.S.C. § 119 to Japanese Patent Application 2003-305540, filed on Aug. 28, 2003, the entire content of which is incorporated herein by reference.

FIELD OF THE INVENTION

This invention generally relates to a load detecting seat for detecting a load applied to a vehicle seat by a load sensor with a strain gage and the like. More particularly, the present invention pertains to an installing structure of the load sensor on the vehicle seat.

BACKGROUND

A known load detecting seat is disclosed in Japanese patent Laid-open publication No.2002-172962 (in the fourth and fifth pages). The known load detecting seat includes rail members (e.g. lower rails and upper rails), a seat cushion having a seating surface, seat cushion brackets and a seat pan. The rail members including the lower rails and the upper rails are provided at the right and the left of the seating surface of the seat cushion for supporting the seat cushion of the load detecting seat, and each upper rail is slidable on each lower rail. The seat pan is supported by the upper rails through the seat cushion brackets. In such configuration, the seat cushion brackets are fixed to the upper rails with bolts which are specially treated. Specifically, each bolt includes a through-hole passing through a center portion of the bolt for housing a load sensor (e.g. strain sensor) which detects a load applied to the seating surface. Four bolts including sensors are provided at right, left, front and rear side of the seating surface respectably so as to detect the load applied to the seating surface.

According to the disclosed load detecting seat having the aforementioned configuration, the specially treated bolts need to be used for connecting the seat brackets to the upper rails, at the same time, four sensors need to be provided for detecting the loads applied to the right, left, front and rear portion of the seating surface. The more the number of the sensor is increased, the more the cost of the load detecting seat is increased. Further, it requires high accuracy and delicate work to open such through-hole at the center portion of the bolt and insert the load sensor into the through-hole of the bolt precisely. In the light of such operational difficulty, the cost of the load detecting seat is further increased.

Thus, a need exists for a load detecting seat to have a construction by which the load sensor can be easily mounted to the load detecting seat, at the same time, a cost increase of such load detecting seat can be prevented.

SUMMARY OF THE INVENTION

According to an aspect of the present invention, a load detecting seat comprises a pair of supporting members provided at the right and left sides of a seating surface of a seat cushion of the load detecting seal for supporting the seat cushion on a floor, a seat frame serving as a skeletal structure of the load detecting seat, a load detecting means provided between one supporting member and the seat frame for detecting a load applied to the seating surface of the seat cushion of the load detecting seat, a rod bridging the one supporting member and the other supporting member and securely fixed to be unrotatably relative to the one supporting member at a fixing portion of the rod, a connecting member fixed to the rod and rotatably supported by the seat frame for applying a torsion force to the rod due to the load applied to the seat frame, and the load detecting means is provided at a portion of the rod.

According to another aspect of the present invention, a load detecting seat, comprises a pair of supporting members provided at the right and left sides of a seating surface of a seat cushion of the load detecting seat for supporting the seat cushion on a floor, a seat frame serving as a skeletal structure of the load detecting seat, a load detecting means provided between one supporting member and the seat frame for detecting a load applied to the seating surface of the seat cushion of the load detecting seat, a connecting member bridging the one supporting member and the other supporting member, fixed securely to the one supporting member at a fixing portion of the connecting member and rotatably supported by the seat frame for generating a torsion force due to the load applied to the seat frame, and the load detecting means is provided at a portion of the connecting member.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and additional features and characteristics of the present invention will become more apparent from the following detailed description considered with reference to the accompanying drawings, wherein:

FIG. 1 illustrates an oblique perspective figure of a skeletal structure of a load detecting seat according to an embodiment of the present invention;

FIG. 2 illustrates a perspective view in which a seat cushion, a seat back and a head rest are attached to the skeletal structure of the load detecting seat in FIG. 1;

FIG. 3 illustrates a perspective view of the load detecting seat along a line which is passing through approximately a center of a rod, and

FIG. 4 illustrates an oblique perspective figure of a skeletal structure of a load detecting seat according to another embodiment of the present invention.

DETAILED DESCRIPTION

An embodiment of the present invention will be explained hereinbelow referring to attached drawings.

FIG. 1 illustrates a configuration of a load detecting seat 1 (hereinbelow referred to as a seat 1) applied as a vehicle seat to the vehicle. In the following explanation of the embodiment of the present invention, the upper portion of the seat 1 (above an upper rail 3 of the seat 1) will be explained as a main unit of the seat 1 hereinbelow.

The seat 1 includes a seat supporting mechanisms 10 provided lower portion of the seat 1 and fixed on a vehicle floor, a seat cushion SC provided at the upper portion of the seat supporting mechanism 10 and having a seating surface SS, a seat back SB provided at the rear of the seat 1 and being rotatable with a predetermined angle relative to the seating surface SS in the cross direction of the seat 1 about a rod 23, and a head rest SH being height-adjustable thereof and provided at upper portion of the seat back SB for supporting an occupant's head. The seat 1 in FIG. 1 includes a mechanism (slide mechanism) for maintaining the seat 1 slid in longitudinal direction of the vehicle at a determined position and another mechanism (reclining mechanism) for maintaining the seat back SB at a predetermined reclining angle. Such mechanisms including known configurations, so that the explanation will be abbreviate hereinbelow.

The seat supporting mechanism 10 for supporting the main unit of the seat 1 relative to the vehicle floor includes supporting members, rods 21, 22, and links 5, 6 (connecting member). Specifically, the supporting members include lower rails 2, upper rails 3 and upper brackets 4, 7.

The lower rail 2 made of pressed metal board is extending straight and having a bottom portion and two wall portions which sandwich the bottom portion therebetween. Thus, a cross sectional shape of the lower rail 2 is approximately an U-shape as shown in FIG. 3. Further, each end portion of the wall portions of the lower rail 2 is extending inward in width direction thereof. The lower rail 2 is provided in pairs on the vehicle floor at both sides of the seating surface SS in seat width direction. Such lower rails 2 are fixed to the vehicle floor to be horizontal relative to the vehicle floor by fixing members such as bolts (not shown).

The upper rail 3 made of same pressing metal board as the lower rail 2 is also extending straight and having a top portion and two wall portions which sandwich the top portion therebetween. Thus, a cross sectional shape of the upper rail 3 is approximately an inverted U-shape as shown in FIG. 3. Further, each end portions of the wall portions of the upper rail 3 is extending outward then extending upward to be guided by the both ends of the lower rail 2 extending inward as shown in FIG. 3, so that the upper rail 3 is slidable on the lower rail 2 in longitudinal direction thereof. In such configuration, a roller 17 is provided at lower portion of the upper rail 3, so that the upper rail 3 is smoothly slidable in longitudinal direction thereof on the lower rail 3 fixed on the vehicle floor.

As shown in FIG. 3, a U-shaped upper bracket 4 includes a bottom portion and two side walls which sandwich the bottom portion therebetween to be U-shape in cross section, Two circular-shaped first bearing portions are provided at respective front portions of the side walls of one upper bracket 4, and two circular-shaped second bearing portions are provided at respective rear portions of the side walls of the one upper bracket 4. Such upper bracket 4 is fixed to one upper rail 3 (right upper rail in FIG. 3) by welding at several portions thereof Respective first bearing portions include through-holes 4 a through which the rod 21 is penetrated, and respecting second bearing portions include through-holes 4 b through which the rod 22 is penetrated.

Another upper bracket 7 being inverted L-shape in cross section from front of the seat 1 is provided at the other upper rail 3 at which the upper bracket 4 is not provided (left upper rail in FIG. 3) at an upper portion thereof. A bottom portion of the inverted L-shaped upper bracket 7 is fixed to the other upper rail 3 at several portions thereof. The inverted L-shaped upper bracket 7 includes a through-hole 7 a and a through-hole 7 b. The through-hole 7 a is paired with the through holes 4 a and having a same diameter as the through hole 4 a have. The through-hole 7 b is paired with the through holes 4 b and having same diameter as the through-hole 4 b have.

The rod 21 being hollowed is penetrated in seat width direction through the through-holes 4 a and the through-hole 7 a which sandwich the seating surface SS. A portion of the rod 21 (e.g. an end portion or a near end portion thereof is fixed at one first bearing portion by welding from inside or outside thereof. Thus, the rod 21 penetrated through the through holes 4 a and the through hole 7 a are fixed at one through-hole 4 a so as to be unrotatably supported at three points. One ends the links 5 are unrotatably welded to the rod 21 to be at the same angel relative to the rod 21 near the through hole 4 a and the through hole 7 a. The other ends of the links 5 are rotatably attached to the front portions of a seat cushion brackets 11 (seat frame) with caulking pins.

The rod 22 being hollowed is penetrated in seat width direction through the through-holes 4 b and the through-hole 7 b which sandwich the seating surface SS at rear portion thereof. A portion of the rod 22 (e.g. an end portion or a near end portion thereof) is fixed at one second bearing portion by welding from inside or outside thereof. Thus, the rod 22 penetrated through the through holes 4 b and the through hole 7 b are fixed at one through-hole 4 b so as to be unrotatably supported at three points. One ends of the links 6 are unrotatably welded to the rod 22 to be at the same angel relative to the rod 22 near the through hole 4 b and the through hole 7 b. The other ends of the links 6 are rotatably attached to the rear portions of the seat cushion brackets 11 (seat frame) with caulking pins.

A load sensor 8 (load detecting means) includes a strain gage inside thereof for detecting resistance variation in proportion to load based on a transformation of the strain gage due to a load applied on the seating surface SS. The load sensor 8 is attached at an outer peripheral surface of the rod 21 by fixing means such as an adhesive bonding between two through-holes 4 a formed at the first bearing portions of the one upper bracket 4. The load sensor 8 is leaned at certain degrees, preferably 45 degrees, relative to the axis of the rod 21. Thus, the load sensor 8 detects the load applied to the seating surface SS based on a torsion force of the rod 21.

The load sensor 9 (load detecting means) is attached at an outer peripheral surface of the rod 22 by fixing means such as an adhesive bonding between two through-holes 4 b formed at the second bearing portions of the one upper bracket 4. The load sensor 9 is leaned at certain degrees, preferably 45 degrees, relative to the axis of the rod 22. Thus, the load sensor 9 detects the load applied to the seating surface SS based on a torsion force of the rod 22.

Thus, it is preferable that the load sensor 8 is provided between a portion at which the rod 21 is unrotatably fixed (the one through-hole 4 a) and a portion at which the link 5 is provided, where the deformation of the rod 21 due to the load applied to the rod 21 is relatively large. At the same time, it is also preferable that the load sensor 9 is provided between a portion at which the rod 22 is unrotatably fixed (the one through-hole 4 b) and a portion at which the link 6 is provided, where the deformation of the rod 22 due to the load applied to the rod 22 is relatively large.

The load detecting process when an occupant seats on the seating surface SS of the seat, and a load is applied on the seating surface SS will be explained as follows.

When the occupant seats on the seating surface SS, and the load is applied to the seat cushion SC and the seat back frame SB, the load is transmitted to the seat supporting mechanism 10 supporting the seat 1 relative to a vehicle floor 20. The load applied to the seat 1 is further applied to the paired links 5 provided at front and the paired links 6 provided at rear. Then, the load applied to the front and rear links 5 and 6 generates moments relative to the front and rear links 5 and 6. At this point, the rod 21 at which the links 5 are fixed is unrotatably fixed at one fixing portion (the one through hole 4 a) and the rod 22 at which the links 6 are fixed is unrotatably fixed at one fixing portion (the one through hole 4 b), so that the torsion forces in anticlockwise direction being in proportion to the load are generated at the rods 21 and 22. Such torsion forces are detected by the load sensors 8 and 9 provided on the rods 21 and 22.

According to the known load detecting seat, four load sensors are provided relative to the seating surface SS, however, according to an aspect of the embodiment of the present invention, only two load sensors arc provided on at least one upper rail (rail member) in longitudinal direction of the seat, so that the cost of the load detecting seat can be reduced. Further, the load sensors 8 and 9 are provided on the surfaces of the rods 21 and 22 so that an assembling process can be simplified.

According to further aspect of the embodiment, the load sensors 8 and 9 detect the load applied to the seating surface SS based on the torsion force which is applied to the rods 21 and 22 through the links 5 and 6 whose respective one ends are fixed to the respective rods. In such configuration, a load signal from the load sensors 8 and 9 are transmitted to a determining device (signal processing device) (not shown) classifying the occupant based on the load signal which is electrically wired to one rail member, so that the wiring can be simplified.

In the embodiment of the present invention, the links 5 are provided as single bodies to the rod 21 provided at front portion of the vehicle, and the links 6 are provided as single bodies to the rod 22 provided at rear portion of the vehicle, however, the rod 21 and the links 5 may be molded integrally (connecting member), and the rod 22 and the links 6 may be molded integrally (connecting member) as shown in FIG. 4. In this configuration, the number of the components of the load detecting seat 1 can be reduced.

Further, the bearing portions of the upper bracket 4 includes the pair of through-holes 4 a at front portion of the upper bracket 4 and the pair of through-holes 4 b at rear portion of the upper bracket 4 in the embodiment, however, the through-hole 4 a and the through hole 4 b may be formed at only the inner bearing portions. In this configuration, the rod 21 and 22 are penetrated through the through hole 4 a and the through hole 4 b and welded at the outer bearing portion from inside of the vehicle seat.

The principles, preferred embodiment and mode of operation of the present invention have been described in the foregoing specification. However, the invention which is intended to be protected is not to be construed as limited to the particular embodiments disclosed. Further, the embodiments described herein are to be regarded as illustrative rather than restrictive. Variations and changes may be made by others, and equivalents employed, without departing from the sprit of the present invention. Accordingly, it is expressly intended that all such variations, changes and equivalents which fall within the spirit and scope of the present invention as defined in the claims, be embraced thereby. 

1. A load detecting seat, comprising: a pair of supporting members provided at the right and left sides of a seating surface of a seat cushion of the load detecting seat for supporting the seat cushion on a floor; a seat frame serving as a skeletal structure of the load detecting seat; a load detecting means provided between one supporting member and the seat frame for detecting a load applied to the seating surface of the seat cushion of the load detecting seat; a rod bridging the one supporting member and the other supporting member and securely fixed to be unrotatably relative to the one supporting member at a fixing portion of the rod; a connecting member fixed to the rod and rotatably supported by the seat frame for applying a torsion force to the rod due to the load applied to the seat frame, and the load detecting means is provided at a portion of the rod.
 2. A load detecting seat according to claim 1, wherein the load detecting means is provided between the fixing portion of the rod and the connecting member.
 3. A load detecting seat according to claim 1, wherein a pair of the rods are provided to be extending in width direction relative to the seat cushion and spaced in longitudinal direction relative to the seat cushion, and that the load detecting means is provided in pairs on the rods, each at the same side thereof.
 4. A load detecting seat according to claim 2, wherein a pair of the rods are provided to be extending in width direction relative to the seat cushion and spaced in longitudinal direction relative to the scat cushion, and that the load detecting means is provided in pairs on the rods, each at the same side thereof.
 5. A load detecting seat according to claim 3, wherein the load detecting means is provided at the rod to be inclined relative to axis of the rod.
 6. A load detecting seat according to claim 5, wherein the load detecting means is provided at the rod to be inclined at 45 degrees relative to axis of the rod.
 7. A load detecting seat according to claim 4, wherein the load detecting means is provided at the rod to be inclined relative to axis of the rod.
 8. A load detecting seat according to claim 7, wherein the load detecting means is provided at the rod to be inclined at 45 degrees relative to axis of the rod.
 9. A load detecting seat, comprising: a pair of supporting members provided at the right and left sides of a seating surface of a seat cushion of the load detecting seat for supporting the seat cushion on a floor; a seat frame serving as a skeletal structure of the load detecting seat; a load detecting means provided between one supporting member and the seat frame for detecting a load applied to the seating surface of the seat cushion of the load detecting seat; a connecting member bridging the one supporting member and the other supporting member, fixed securely to the one supporting member at a fixing portion of the connecting member and rotatably supported by the seat frame for generating a torsion force due to the load applied to the seat frame, and the load detecting means is provided at a portion of the connecting member.
 10. A load detecting seat according to claim 9, wherein a pair of connecting members are provided to be extending in width direction relative to the seat cushion and spaced in longitudinal direction relative to the seat cushion, and that the load detecting means is provided in pairs on the connecting members, each at the same side thereof.
 11. A load detecting seat according to claim 10, wherein the load detecting means is provided at the connecting member to be inclined relative to axis of the rod.
 12. A load detecting seat according to claim 11, wherein the load detecting means is provided at the connecting member to be inclined at 45 degrees relative to axis of the rod. 